MD_DataIdentification

Count

Component

Title

Abstract

1

ETOPO1 1 Arc-Minute Global Relief Model

In August 2008, the National Geophysical Data Center (NGDC), an office of the National
Oceanic and Atmospheric Administration (NOAA), developed the ETOPO1 Global Relief
Model as an improvement to the ETOPO2v2 Global Relief Model. ETOPO1 is available in
"Ice Surface" (top of Antarctic and Greenland ice sheets) and "Bedrock" (base of the
ice sheets) versions. Both versions of ETOPO1 were generated from diverse global and
regional digital data sets, which were shifted to common horizontal and vertical datums,
and then evaluated and edited as needed. Bathymetric, topographic, and shoreline data
used in ETOPO1 were obtained from NGDC, Antarctic Digital Database (ADD), European
Ice Sheet Modeling Initiative (EISMINT), Scientific Committee on Antarctic Research
(SCAR), Japan Oceanographic Data Center (JODC), Caspian Environment Programme (CEP),
Mediterranean Science Commission (CIESM), National Aeronautics and Space Administration
(NASA), National Snow and Ice Data Center (NSIDC), Scripps Institute of Oceanography
(SIO), and Leibniz Institute for Baltic Sea Research (LIBSR). ETOPO1 is vertically
referenced to sea level, and horizontally referenced to the World Geodetic System
of 1984 (WGS 84). Cell size for ETOPO1 is 1 arc-minute.

Not to be used for navigation. Although these data are of high quality and useful
for planning and modeling purposes, they are not suitable for navigation. For navigation,
please refer to the NOS nautical chart series.

While every effort has been made to ensure that these data are accurate and reliable
within the limits of the current state of the art, NOAA cannot assume liability for
any damages caused by any errors or omissions in the data, nor as a result of the
failure of the data to function on a particular system. NOAA makes no warranty, expressed
or implied, nor does the fact of distribution constitute such a warranty.

2

These data not to be used for navigation. Although these data are of high quality
and useful for planning and modeling purposes, they are not suitable for navigation.
For official navigation products, please refer to the U.S. nautical charts available
from the NOAA Office of Coast Survey: http://www.nauticalcharts.noaa.gov.

All datasets obtained by NGDC were converted to common horizontal and vertical datums
of WGS 84 and sea level, respectively, using FME. They were also converted to common
file format, ESRI point shapefiles, for visualization and inspection.

1

2008-06-25T00:00:00

Datasets were visually inspected with ArcGIS for identification and editing of data
anomalies. Datasets were then compared with overlapping datasets to ensure data consistency.

1

2008-06-30T00:00:00

Coastline datasets were adjusted to fit satellite imagery.

1

2008-07-10T00:00:00

xyz files of the Measured and Estimated Seafloor Topography data (between -500 m and
0 m) were surfaced using GMT's 'surface' tool onto a 1 arc-minute cell size grid that
interpolated to fill empty cells. Points extracted along the GSHHS coastline were
also included, at -1 m elevation, to force bathymetric interpolation into the coastal
zone. The resulting Arc ASCII grid was clipped to the coastline and the -120 m contour
to remove values over land and non-coastal waters.

1

2008-07-18T00:00:00

xyz files for each input dataset were gridded using MB-System's 'mbgrid' tool, which
utilizes a high-tension spline interpolation method to fill grid cells with no input
elevation values. Preferential weighting was given to the NSIDC Antarctica RAMP topography
dataset. Least weight was given to the global datasets and the interpolated bathymetric
surface. Gridding was performed in 16 regional tiles, each with a 5% data buffer.
The grids were imported in ArcGIS and seamlessly merged to create the final global
relief model.

1

2008-07-31T00:00:00

ETOPO1 was bult as a global, grid-registered, 1 arc-minute grid that spans from pole
to pole and from -180 degrees to 180 degrees in longitude. It is 21601 cells by 10801
cells in dimension, with multiple duplicate cells sitting atop the North and South
poles and on the -180 degrees and 180 degrees longitude line. A cell-registered version
(21600 by 10800 cells) was created from the grid-registered version by resampling,
using GMT's 'grdsample' tool. This resampling introduces some flattening of relief,
due to averaging of four grid-registered cell vlaues to produce one cell-registered
value. Both types are global, though the grid-registered version should be considered
the authoritative version. The cell-registered version may be more appropriate for
creating maps and images.